科研之友
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摘要
objective: to characterize the presence, extent, and patterns of dynamic hyperinflation (dh) during treadmill exercise testing in patients with moderate to severe copd. methods: this was a cross-sectional study involving 30 non-hypoxemic patients (fev1= 43 ㊣ 14% of predicted) who were submitted to a cardiopulmonary exercise test on a treadmill at a constant speed (70-80% of maximum speed) to the tolerance limit (tlim). serial inspiratory capacity (ic) maneuvers were used in order to assess dh. results: of the 30 patients studied, 19 (63.3%) presented with dh (dh+ group), having greater pulmonary function impairment at rest than did those without dh (dh- group). none of the variables studied correlated with exercise tolerance in the dh- group, whereas tlim, ic, and perception of dyspnea during exercise did so correlate in the dh+ group (p %26lt; 0.05). in the dh+ group, 7 and 12 patients, respectively, presented with a progressive and a stable pattern of dh (汛ictlim,2min = -0.28 ㊣ 0.11 l vs. 0.04 ㊣ 0.10 l; p %26lt; 0.01). patients with a progressive pattern of dh presented with higher perception of dyspnea/tlim rate and lower exercise tolerance than did those with a stable pattern (354 ㊣ 118 s and 465 ㊣ 178 s, respectively; p %26lt; 0.05). conclusions: the presence of dh is not a universal phenomenon during walking in copd patients, even in those with moderate to severe airflow limitation. in the patients who presented dh, a progressive pattern of dh had a greater impact on exercise tolerance than did a stable pattern of dh.
